A shared communications experience is an event at which groups of communicants engage in the exchange of information and ideas. Such events include business and technical presentations, training sessions, lectures, and meetings. A shared communications experience might also include a teleconferencing session between participants located remotely from one another. Where the event entails the exchange of different forms (e.g., video, text, and audio), the event is commonly characterized as a multimedia event. The exchange of information may be assisted by both non-electronic devices (e.g., view graphs, white boards, and notepads) and electronic devices (e.g., video, computers, and electronic white boards).
FIG. 1 depicts an example of a multimedia event and electronic and non-electronic devices that might be employed to facilitate communication. At the training session, there is a lecturer 110, who presents information to trainees 111-114 seated in the training room 100. To facilitate presentation of the information to the trainees, the lecturer utilizes a view graph machine 120, which projects an image on to a projection screen 125. The lecturer also utilizes an electronic white board 127 for drawing handwritten notes and diagrams.
Shared communications experiences, such as that shown in FIG. 1, are often recorded to allow persons unable to attend the event to benefit from the exchange of information and ideas. The recording also permits attendees to review the event and clarify details that were missed during the live event. A technique for recording such events may include using written notes, such as those that might be taken by one of the trainees 111-114 at the training session. Written notes result in a subjective interpretation of the event that may lack important visual information, such as the speaker's body language and trainees' non-verbal responses to lecture materials as well as audible information such as the speaker's tone of voice. Another drawback is that the written notes are also a subjective interpretation of the event by the scrivener.
Another technique involves recording the audio of the event on audio cassettes. Pure audio recordings can be a more accurate and complete record of the experience than written notes, but are difficult to browse or search. Therefore, if a user of the recording were only interested in hearing a portion of the event where the lecturer 110 answered a question asked by trainee 111, the listener must randomly advance and reverse in the audio recording until stumbling upon the desired segment. As with written notes, visual cues from the event are lost.
A commonly preferred technique for recording events is using a video camcorder operated by human operator. A video recording provides the most accurate representation of the event, but often does not provide adequate coverage of the whole experience because of the limited field of view of conventional video camcorders. Furthermore, the view of the event captured in the video recording has been subjectively selected by the human operator, and this view may not coincide with the view of the event desired by a user of the video recording. For example, the camera operator may focus on the view graphs projected onto the projection screen 125 while the lecturer 110 is emphasizing a point and miss the gestures of the lecturer 110 used to illustrate the point. Consequently, users of the recording will never see these gestures. Optimally, both the view graphs and the lecturer should be captured such that users of the recording have the option to choose which view should be presented. But, under conventional single camera recording systems, users of the video recording are limited to the view subjectively selected by the camera operator.
Alternatively, the video recording can be generated using a more sophisticated technique employing multiple cameras and other equipment as described in Braun et al U.S. Pat. No. 5,187,571, Feb. 16, 1993, which cameras and equipment facilitate the capturing and contiguous merging of multiple views of an event to form an aggregate field view. Under this approach, cameras 130, 140, and 150 could be used to capture Regions A, B, and C, respectively, of the training session as shown in FIG. 1. This approach provides a more faithful reproduction of the entire event than any approach previously mentioned, but production of the recording can be cost-prohibitive and the quality of the recording is limited by the resolution of the medium on which the recording is stored. By capturing a full view of the event, the resolution of any aspect of the event is significantly diminished. For example, by recording a full view of the lecture session comprising the fields of view of cameras 130, 140, and 150, the notation on the white board 127 and the text on the view graphs projected on screen 125 may be illegible. This is because video is a relatively poor medium for recording certain information, such as text written on a white board and in view graphs projected on a screen.
Even with sophisticated recording techniques, the video recording may be of little benefit to a user in browsing, reviewing, or analyzing the event. Many of the limitations are a result of the analog medium used for storing the recording. Analog recordings are used because of the low costs and wide availability of equipment and storage media such as Video Home System (VHS) video tapes. Technology such as the Society of Motion Picture and Television Engineers (SMPTE) time code, which facilitates indexing video tape, computer-controlled videodisc players, and video cassette recorders (VCRs) may overcome some of the limitations, but others remain. In particular, due to its lack of structure and slow access, analog video tape is difficult to browse to identify quickly points of interest. Similar to the audio recording, locating a point of interest requires that the user randomly advance and reverse in the video recording until stumbling upon the point of interest. Furthermore, once the point of interest has been located, the viewer has limited flexibility, if any, to control the resolution of an aspect of the recording or to disable an unwanted aspect of the recording. For example, under conventional approaches, a viewer would not have the flexibility of increasing the resolution of the audio portion of a recording to increase the audible clarity of a question from trainee 111 to the lecturer 110, or totally disabling the view from camera 140 of Region B.
Another consideration when selecting a mechanism for recording an event is the method of delivering the recorded event to the user. One delivery alternative is to transmit the recording from a service provider to a user over a network in real time. However, a limitation of conventional video recordings is that such recordings are bandwidth intensive and often exceed the bandwidth capabilities of the network and the user's facilities, thereby precluding this alternative as a method of delivering recordings to users.
In view of these drawbacks and shortcomings of conventional approaches to recording shared communication experiences including multimedia events, our objective is a system and method for recording and playing back an event such that a user of the recording can control the aspects of the event being presented. A further objective is to facilitate browsing and searching through a recording to locate a point of interest in the recorded event. Another objective is to record events such that the aspects of the event delivered to the user can be adapted to meet constraints of the network, such as bandwidth limitations, and the user's equipment.